1/*
2 * Watchdog driver for Freescale STMP37XX/STMP378X
3 *
4 * Author: Vitaly Wool <vital@embeddedalley.com>
5 *
6 * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
7 * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
8 */
9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/fs.h>
12#include <linux/miscdevice.h>
13#include <linux/watchdog.h>
14#include <linux/platform_device.h>
15#include <linux/spinlock.h>
16#include <linux/uaccess.h>
17#include <linux/module.h>
18
19#include <mach/platform.h>
20#include <mach/regs-rtc.h>
21
22#define DEFAULT_HEARTBEAT	19
23#define MAX_HEARTBEAT		(0x10000000 >> 6)
24
25/* missing bitmask in headers */
26#define BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER     0x80000000
27
28#define WDT_IN_USE		0
29#define WDT_OK_TO_CLOSE		1
30
31#define WDOG_COUNTER_RATE	1000 /* 1 kHz clock */
32
33static DEFINE_SPINLOCK(stmp3xxx_wdt_io_lock);
34static unsigned long wdt_status;
35static const int nowayout = WATCHDOG_NOWAYOUT;
36static int heartbeat = DEFAULT_HEARTBEAT;
37static unsigned long boot_status;
38
39static void wdt_enable(u32 value)
40{
41	spin_lock(&stmp3xxx_wdt_io_lock);
42	__raw_writel(value, REGS_RTC_BASE + HW_RTC_WATCHDOG);
43	stmp3xxx_setl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
44	stmp3xxx_setl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
45			REGS_RTC_BASE + HW_RTC_PERSISTENT1);
46	spin_unlock(&stmp3xxx_wdt_io_lock);
47}
48
49static void wdt_disable(void)
50{
51	spin_lock(&stmp3xxx_wdt_io_lock);
52	stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
53			REGS_RTC_BASE + HW_RTC_PERSISTENT1);
54	stmp3xxx_clearl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
55	spin_unlock(&stmp3xxx_wdt_io_lock);
56}
57
58static void wdt_ping(void)
59{
60	wdt_enable(heartbeat * WDOG_COUNTER_RATE);
61}
62
63static int stmp3xxx_wdt_open(struct inode *inode, struct file *file)
64{
65	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
66		return -EBUSY;
67
68	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
69	wdt_ping();
70
71	return nonseekable_open(inode, file);
72}
73
74static ssize_t stmp3xxx_wdt_write(struct file *file, const char __user *data,
75	size_t len, loff_t *ppos)
76{
77	if (len) {
78		if (!nowayout) {
79			size_t i;
80
81			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
82
83			for (i = 0; i != len; i++) {
84				char c;
85
86				if (get_user(c, data + i))
87					return -EFAULT;
88				if (c == 'V')
89					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
90			}
91		}
92		wdt_ping();
93	}
94
95	return len;
96}
97
98static const struct watchdog_info ident = {
99	.options	= WDIOF_CARDRESET |
100			  WDIOF_MAGICCLOSE |
101			  WDIOF_SETTIMEOUT |
102			  WDIOF_KEEPALIVEPING,
103	.identity	= "STMP3XXX Watchdog",
104};
105
106static long stmp3xxx_wdt_ioctl(struct file *file, unsigned int cmd,
107	unsigned long arg)
108{
109	void __user *argp = (void __user *)arg;
110	int __user *p = argp;
111	int new_heartbeat, opts;
112	int ret = -ENOTTY;
113
114	switch (cmd) {
115	case WDIOC_GETSUPPORT:
116		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
117		break;
118
119	case WDIOC_GETSTATUS:
120		ret = put_user(0, p);
121		break;
122
123	case WDIOC_GETBOOTSTATUS:
124		ret = put_user(boot_status, p);
125		break;
126
127	case WDIOC_SETOPTIONS:
128		if (get_user(opts, p)) {
129			ret = -EFAULT;
130			break;
131		}
132		if (opts & WDIOS_DISABLECARD)
133			wdt_disable();
134		else if (opts & WDIOS_ENABLECARD)
135			wdt_ping();
136		else {
137			pr_debug("%s: unknown option 0x%x\n", __func__, opts);
138			ret = -EINVAL;
139			break;
140		}
141		ret = 0;
142		break;
143
144	case WDIOC_KEEPALIVE:
145		wdt_ping();
146		ret = 0;
147		break;
148
149	case WDIOC_SETTIMEOUT:
150		if (get_user(new_heartbeat, p)) {
151			ret = -EFAULT;
152			break;
153		}
154		if (new_heartbeat <= 0 || new_heartbeat > MAX_HEARTBEAT) {
155			ret = -EINVAL;
156			break;
157		}
158
159		heartbeat = new_heartbeat;
160		wdt_ping();
161		/* Fall through */
162
163	case WDIOC_GETTIMEOUT:
164		ret = put_user(heartbeat, p);
165		break;
166	}
167	return ret;
168}
169
170static int stmp3xxx_wdt_release(struct inode *inode, struct file *file)
171{
172	int ret = 0;
173
174	if (!nowayout) {
175		if (!test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
176			wdt_ping();
177			pr_debug("%s: Device closed unexpectedly\n", __func__);
178			ret = -EINVAL;
179		} else {
180			wdt_disable();
181			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
182		}
183	}
184	clear_bit(WDT_IN_USE, &wdt_status);
185
186	return ret;
187}
188
189static const struct file_operations stmp3xxx_wdt_fops = {
190	.owner = THIS_MODULE,
191	.llseek = no_llseek,
192	.write = stmp3xxx_wdt_write,
193	.unlocked_ioctl = stmp3xxx_wdt_ioctl,
194	.open = stmp3xxx_wdt_open,
195	.release = stmp3xxx_wdt_release,
196};
197
198static struct miscdevice stmp3xxx_wdt_miscdev = {
199	.minor = WATCHDOG_MINOR,
200	.name = "watchdog",
201	.fops = &stmp3xxx_wdt_fops,
202};
203
204static int __devinit stmp3xxx_wdt_probe(struct platform_device *pdev)
205{
206	int ret = 0;
207
208	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
209		heartbeat = DEFAULT_HEARTBEAT;
210
211	boot_status = __raw_readl(REGS_RTC_BASE + HW_RTC_PERSISTENT1) &
212			BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER;
213	boot_status = !!boot_status;
214	stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
215			REGS_RTC_BASE + HW_RTC_PERSISTENT1);
216	wdt_disable();		/* disable for now */
217
218	ret = misc_register(&stmp3xxx_wdt_miscdev);
219	if (ret < 0) {
220		dev_err(&pdev->dev, "cannot register misc device\n");
221		return ret;
222	}
223
224	printk(KERN_INFO "stmp3xxx watchdog: initialized, heartbeat %d sec\n",
225		heartbeat);
226
227	return ret;
228}
229
230static int __devexit stmp3xxx_wdt_remove(struct platform_device *pdev)
231{
232	misc_deregister(&stmp3xxx_wdt_miscdev);
233	return 0;
234}
235
236#ifdef CONFIG_PM
237static int wdt_suspended;
238static u32 wdt_saved_time;
239
240static int stmp3xxx_wdt_suspend(struct platform_device *pdev,
241				pm_message_t state)
242{
243	if (__raw_readl(REGS_RTC_BASE + HW_RTC_CTRL) &
244		BM_RTC_CTRL_WATCHDOGEN) {
245		wdt_suspended = 1;
246		wdt_saved_time = __raw_readl(REGS_RTC_BASE + HW_RTC_WATCHDOG);
247		wdt_disable();
248	}
249	return 0;
250}
251
252static int stmp3xxx_wdt_resume(struct platform_device *pdev)
253{
254	if (wdt_suspended) {
255		wdt_enable(wdt_saved_time);
256		wdt_suspended = 0;
257	}
258	return 0;
259}
260#else
261#define stmp3xxx_wdt_suspend	NULL
262#define stmp3xxx_wdt_resume	NULL
263#endif
264
265static struct platform_driver platform_wdt_driver = {
266	.driver = {
267		.name = "stmp3xxx_wdt",
268	},
269	.probe = stmp3xxx_wdt_probe,
270	.remove = __devexit_p(stmp3xxx_wdt_remove),
271	.suspend = stmp3xxx_wdt_suspend,
272	.resume = stmp3xxx_wdt_resume,
273};
274
275module_platform_driver(platform_wdt_driver);
276
277MODULE_DESCRIPTION("STMP3XXX Watchdog Driver");
278MODULE_LICENSE("GPL");
279
280module_param(heartbeat, int, 0);
281MODULE_PARM_DESC(heartbeat,
282		 "Watchdog heartbeat period in seconds from 1 to "
283		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
284		 __MODULE_STRING(DEFAULT_HEARTBEAT));
285
286MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
287